I am so upset. My female yorkie Roxy has had a complete personality change after she got spayed. She is a big bully with my male yorkie Gibson. Gibson is significantly smaller than Roxy so this worries me. She will run full force at him and bulldoze him over, start biting his ear, pounce at him etc. If Gibson tries to chew on a bone, she will go over and growl at him and take it away and then try to hide it. I have tried disciplining her but she does not stop. Has anyone experienced this?